R data frame extracting non-sequential columns and creating new sub data frames

问题

I have a data frame consisting of 25 columns and 30,000 rows. I want to create sub-data frames that contain all rows but only certain columns that are in non-sequential order. As an example, a sub data frame containing columns 1, 12, 15, and 25.

I have been playing around with lapply but I dont know how to create the sub data frames with columns that are in non-sequential order.

Thanks.

回答1:

Information from data.frames can be extracted by using the indices of a data.frame's rows, columns, or both.

The general form is of:

dataset[rows_wanted, cols_wanted]

Omitting one of those returns all of what was omitted. For example, dataset[c(1, 2, 3), ] would return rows one through three, and all the columns.

Thus, for your problem, you can simply do:

dataset[, c(1, 2, 12, 25)]

来源：https://stackoverflow.com/questions/19757554/r-data-frame-extracting-non-sequential-columns-and-creating-new-sub-data-frames